Circular Orbits:
An object needs to at least be going 8 km/s to go into an orbit around the Earth. If it is going slower it would fall back to the Earth. Back when Newton calculated this speed he thought that it was unachievable, but in today's world special rockets make it possible. When an object is propelled at the speed it is continually falling around the Earth under the influence of gravity. When it is moving tangent to the Earth, it continues in a circular path at a constant speed. Gravity does not pull the object in motion; no work is done, the direction is just continually changed. The speed and the distance are both constant in a circular orbit, meaning that the KE and PE are constant as well.
The moon is in circular orbit around the Earth. Circular Orbit has an eccentricity equal to 0 as presented below. The distance from the foci is constant in an elliptical orbit, but as it comes closer together, the orbit becomes more circular. An example would be an object rotating about an axis lined through the center of the mass perpendicular to the object in motion. Circular Orbits have change in direction but constant in magnitude. Yes it is true that no work is being done but the object does move in a perpendicular motion and it stays in a circular motion due to the centripetal force.
three orbit types
How was circular orbit discovered? German mathematician and astronomer Johannes Kepler and his three laws on planetary motion. His first law was that the orbit of every planet is an ellipse with the sum at a focus. His second law, that a line joining a planet and the sun spreads an equal area during an equal interval of time. His third law, planets distant from the sun have longer orbital periods than closer planets.
This is a video about circular orbits: http://videos.howstuffworks.com/nasa/3570-earth-has-a-perfect-orbit-video.htm
Gravity supplies the essential centripetal force to hold a satellite in orbit around the earth. The cicular orbit is a special case since orbits are generally ellipses. Setting te gravity force from the universal law of gravity equal to the required centripetal force yields the description of the orbit. The orbit can be expressed in terms of acceleration due to gravity.
File:Geoz wb en.svg
Differences Between the Orbit Types:
Circular: Elliptical:
speed: 8 km/s speed: > 8 km/s
KE & PE are equal KE & PE are proportionate
no gravitational force some component of gravitational force
*there is a point where a satellite is launched so fast that it leaves the Earth's gravitational influence (Escape Speed)
In this image above, we see that in the case of projectice A and projecile B, their velocity does not reach higher than 8 km/s. When the velocity does reach 8 km/s, then the path taken will be that of projectile C. In this case of a circular orbit, the object is continually following because of the effect gravity has, while also moving tangent to the earth, making it move in a circle. When the speed exceed 8 km/s, it will turn into an elleptical orbit, and eventually if fast enough, it will leave orbit just like projectile E.
The diagram to the left represents a circular orbit. To find the circular velocity, you must use variables to the left and plug them into the equation v = √{G(M + m)/R}. M represents mass, the R represents the radius of the orbit, and there is also a gravitational constant influenced in the equation. Though this equation works for certain problems, it is hardly ever achieved. When it is though, it is said to have an eccentricity of zero. This is very rare though.
An object needs to at least be going 8 km/s to go into an orbit around the Earth. If it is going slower it would fall back to the Earth. Back when Newton calculated this speed he thought that it was unachievable, but in today's world special rockets make it possible. When an object is propelled at the speed it is continually falling around the Earth under the influence of gravity. When it is moving tangent to the Earth, it continues in a circular path at a constant speed. Gravity does not pull the object in motion; no work is done, the direction is just continually changed. The speed and the distance are both constant in a circular orbit, meaning that the KE and PE are constant as well.
The moon is in circular orbit around the Earth. Circular Orbit has an eccentricity equal to 0 as presented below. The distance from the foci is constant in an elliptical orbit, but as it comes closer together, the orbit becomes more circular. An example would be an object rotating about an axis lined through the center of the mass perpendicular to the object in motion. Circular Orbits have change in direction but constant in magnitude. Yes it is true that no work is being done but the object does move in a perpendicular motion and it stays in a circular motion due to the centripetal force.
How was circular orbit discovered? German mathematician and astronomer Johannes Kepler and his three laws on planetary motion. His first law was that the orbit of every planet is an ellipse with the sum at a focus. His second law, that a line joining a planet and the sun spreads an equal area during an equal interval of time. His third law, planets distant from the sun have longer orbital periods than closer planets.
This is a video about circular orbits:
http://videos.howstuffworks.com/nasa/3570-earth-has-a-perfect-orbit-video.htm
Gravity supplies the essential centripetal force to hold a satellite in orbit around the earth. The cicular orbit is a special case since orbits are generally ellipses. Setting te gravity force from the universal law of gravity equal to the required centripetal force yields the description of the orbit. The orbit can be expressed in terms of acceleration due to gravity.
Differences Between the Orbit Types:
Circular: Elliptical:
speed: 8 km/s speed: > 8 km/s
KE & PE are equal KE & PE are proportionate
no gravitational force some component of gravitational force
*there is a point where a satellite is launched so fast that it leaves the Earth's gravitational influence (Escape Speed)
In this image above, we see that in the case of projectice A and projecile B, their velocity does not reach higher than 8 km/s. When the velocity does reach 8 km/s, then the path taken will be that of projectile C. In this case of a circular orbit, the object is continually following because of the effect gravity has, while also moving tangent to the earth, making it move in a circle. When the speed exceed 8 km/s, it will turn into an elleptical orbit, and eventually if fast enough, it will leave orbit just like projectile E.
The diagram to the left represents a circular orbit. To find the circular velocity, you must use variables to the left and plug them into the equation v = √{G(M + m)/R}. M represents mass, the R represents the radius of the orbit, and there is also a gravitational constant influenced in the equation. Though this equation works for certain problems, it is hardly ever achieved. When it is though, it is said to have an eccentricity of zero. This is very rare though.